40 CFR 142.62 - Variances and exemptions from the maximum contaminant levels for organic and inorganic chemicals.
(a) The Administrator, pursuant to section 1415(a)(1)(A) of the Act hereby identifies the technologies listed in paragraphs (a)(1) through (a)(54) of this section as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for organic chemicals listed in § 141.61 (a) and (c):
|Contaminant||Best available technologies|
|PTA 1||GAC 2||OX 3|
|(2) Carbon tetrachloride||X||X|
|(8) Vinyl chloride||X|
|(18) Xylense (total)||X||X|
|(21) Aldicarb sulfoxide||X|
|(22) Aldicarb sulfone||X|
|(28) Ethylene dibromide||X||X|
|(30) Heptachlor epoxide||X|
|(49) Oxamyl (Vydate)||X|
|(54) 2,3,7,8-TCDD (Dioxin)||X|
1 Packed Tower Aeration
2 Granular Activated Carbon
3 Oxidation (Chlorination or Ozonation)
(b) The Administrator, pursuant to section 1415(a)(1)(A) of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for the inorganic chemicals listed in § 141.62:
BAT for Inorganic Compounds Listed in § 141.62(b)
|Arsenic 4||5 1, 2, 5, 6, 7, 9, 12|
|Mercury||2 1,4,6 1,7 1|
1 BAT only if influent Hg concentrations ≤10µg/1.
2 BAT for Chromium III only.
3 BAT for Selenium IV only.
4 BATs for Arsenic V. Pre-oxidation may be required to convert Arsenic III to Arsenic V.
5 To obtain high removals, iron to arsenic ratio must be at least 20:1.
(c) A State shall require community water systems and non-transient, non-community water systems to install and/or use any treatment method identified in § 142.62 (a) and (b) as a condition for granting a variance except as provided in paragraph (d) of this section. If, after the system's installation of the treatment method, the system cannot meet the MCL, that system shall be eligible for a variance under the provisions of section 1415(a)(1)(A) of the Act.
(d) If a system can demonstrate through comprehensive engineering assessments, which may include pilot plant studies, that the treament methods identified in § 142.62 (a) and (b) would only achieve a de minimis reduction in contaminants, the State may issue a schedule of compliance that requires the system being granted the variance to examine other treatment methods as a condition of obtaining the variance.
(e) If the State determines that a treatment method identified in paragraph (d) of this section is technically feasible, the Administrator or primacy State may require the system to install and/or use that treatment method in connection with a compliance schedule issued under the provisions of section 1415(a)(1)(A) of the Act. The State's determination shall be based upon studies by the system and other relevant information.
(f) The State may require a public water system to use bottled water, point-of-use devices, point-of-entry devices or other means as a condition of granting a variance or an exemption from the requirements of §§ 141.61 (a) and (c) and 141.62, to avoid an unreasonable risk to health. The State may require a public water system to use bottled water and point-of-use devices or other means, but not point-of-entry devices, as a condition for granting an exemption from corrosion control treatment requirements for lead and copper in §§ 141.81 and 141.82 to avoid an unreasonable risk to health. The State may require a public water system to use point-of-entry devices as a condition for granting an exemption from the source water and lead service line replacement requirements for lead and copper under §§ 141.83 or 141.84 to avoid an unreasonable risk to health.
(g) Public water systems that use bottled water as a condition for receiving a variance or an exemption from the requirements of §§ 141.61 (a) and (c) and 141.62, or an exemption from the requirements of §§ 141.81-141.84 must meet the requirements specified in either paragraph (g)(1) or (g)(2) and paragraph (g)(3) of this section:
(1) The Administrator or primacy State must require and approve a monitoring program for bottled water. The public water system must develop and put in place a monitoring program that provides reasonable assurances that the bottled water meets all MCLs. The public water system must monitor a representative sample of the bottled water for all contaminants regulated under §§ 141.61 (a) and (c) and 141.62 during the first three-month period that it supplies the bottled water to the public, and annually thereafter. Results of the monitoring program shall be provided to the State annually.
(2) The public water system must receive a certification from the bottled water company that the bottled water supplied has been taken from an “approved source” as defined in 21 CFR 129.3(a); the bottled water company has conducted monitoring in accordance with 21 CFR 129.80(g) (1) through (3); and the bottled water does not exceed any MCLs or quality limits as set out in 21 CFR 165.110, part 110, and part 129. The public water system shall provide the certification to the State the first quarter after it supplies bottled water and annually thereafter. At the State's option a public water system may satisfy the requirements of this subsection if an approved monitoring program is already in place in another State.
(3) The public water system is fully responsible for the provision of sufficient quantities of bottled water to every person supplied by the public water system via door-to-door bottled water delivery.
(h) Public water systems that use point-of-use or point-of-entry devices as a condition for obtaining a variance or an exemption from NPDWRs must meet the following requirements:
(2) Before point-of-use or point-of-entry devices are installed, the public water system must obtain the approval of a monitoring plan which ensures that the devices provide health protection equivalent to that provided by central water treatment.
(4) The State must require adequate certification of performance, field testing, and, if not included in the certification process, a rigorous engineering design review of the point-of-use and/or point-of-entry devices.
(5) The design and application of the point-of-use and/or point-of-entry devices must consider the potential for increasing concentrations of heterotrophic bacteria in water treated with activated carbon. It may be necessary to use frequent backwashing, post-contactor disinfection, and Heterotrophic Plate Count monitoring to ensure that the microbiological safety of the water is not compromised.
(6) The State must be assured that buildings connected to the system have sufficient point-of-use or point-of-entry devices that are properly installed, maintained, and monitored such that all consumers will be protected.
(7) In requiring the use of a point-of-entry device as a condition for granting an exemption from the treatment requirements for lead and copper under §§ 141.83 or 141.84, the State must be assured that use of the device will not cause increased corrosion of lead and copper bearing materials located between the device and the tap that could increase contaminant levels at the tap.